More than 1 billion adults worldwide are living with obesity, a figure that has more than doubled since 2010. According to the World Obesity Atlas 2025, the total number of adults with obesity grew from 524 million in 2010 to an estimated 1.13 billion by 2030, a rise of over 115%. That makes obesity one of the most widespread chronic health conditions on the planet, affecting roughly 1 in 7 adults.
How Obesity Is Defined
Obesity is measured using body mass index, or BMI, which divides a person’s weight in kilograms by their height in meters squared. A BMI of 30 or above qualifies as obese. Within that range, there are three classes: Class 1 (BMI 30 to 34.9), Class 2 (BMI 35 to 39.9), and Class 3 (BMI 40 or higher). Class 3 carries the highest health risks and is sometimes called severe obesity.
BMI is an imperfect tool. It doesn’t distinguish between muscle and fat, and it can underestimate or overestimate risk depending on a person’s body composition, age, and ethnicity. Still, it remains the standard screening measure used in global health surveys because it’s simple and consistent across populations.
How Rates Differ by Gender
Obesity affects women at higher rates than men worldwide. About 18% of women over 20 are classified as obese, compared to 14% of men, based on figures from the World Obesity Atlas 2023. That gap has remained consistent over time and is expected to persist. Biological factors like differences in fat storage patterns, hormonal shifts during pregnancy and menopause, and differences in lean muscle mass all contribute. Social factors matter too: in many countries, women face greater barriers to physical activity and have less access to healthcare resources for weight management.
Where Obesity Is Most and Least Common
The prevalence of excess weight varies dramatically by region. The WHO Region of the Americas has the highest rate of overweight and obesity combined, at 67% of the population. South-East Asia and Africa sit at the other end, each around 31%. That gap reflects major differences in food environments, urbanization, income levels, and the availability of processed foods.
High-income countries in the Americas, Europe, and the Middle East have long had elevated obesity rates, but the fastest growth is now happening in low- and middle-income countries. As economies develop, diets shift toward cheaper, calorie-dense processed foods while physical activity declines. This pattern has driven sharp increases in countries across Africa, South-East Asia, and the Pacific Islands over the past two decades.
Obesity in Children
The problem is not limited to adults. Childhood obesity has risen steeply in recent decades, particularly in countries undergoing rapid economic transition. Children who develop obesity face a higher likelihood of remaining obese into adulthood, and they develop related health problems like high blood pressure and insulin resistance earlier in life. The shift toward sedentary screen time, reduced physical education in schools, and aggressive marketing of sugary foods and drinks to children all play a role.
The Economic Cost
Obesity places an enormous financial burden on healthcare systems and economies. A study of eight countries published in BMJ Global Health found that obesity-related costs averaged 1.8% of GDP in 2019. That figure ranged from 0.8% of GDP in India to 2.4% in Saudi Arabia. In dollar terms, per-person costs ran from $17 in India to $940 in Australia, reflecting the wide gap in healthcare spending and treatment access between nations.
These costs come from direct medical expenses (treating diabetes, heart disease, joint problems, and other conditions linked to obesity) and indirect costs like lost productivity, disability, and premature death. By 2060, with no major changes, the economic toll is projected to nearly double, reaching an average of 3.6% of GDP across those same countries. Thailand could see costs climb to nearly 5% of GDP.
Health Risks Linked to Obesity
Obesity increases the risk of more than a dozen serious conditions. The strongest links are with type 2 diabetes, cardiovascular disease, and certain cancers, including breast, colon, and kidney cancer. Excess body fat promotes chronic inflammation, raises blood pressure, disrupts blood sugar regulation, and puts additional mechanical stress on joints. People with obesity are also at higher risk for sleep apnea, fatty liver disease, and depression.
Risk does not increase uniformly. Where fat is stored matters: fat concentrated around the abdomen is more metabolically dangerous than fat carried in the hips and thighs. This is one reason why waist circumference is increasingly used alongside BMI to assess health risk.
Why the Numbers Keep Rising
The global rise in obesity is driven by changes to food systems and daily life that have unfolded over decades. Ultra-processed foods now make up a large share of calories consumed in most countries, and these products are engineered to be inexpensive, convenient, and easy to overconsume. Portion sizes have grown. Physical activity has declined as more people work desk jobs and rely on cars. Urban design in many parts of the world discourages walking and cycling.
Genetics play a real role in individual susceptibility, influencing appetite, metabolism, and fat storage. But genes haven’t changed in the past 40 years. The environment has. The rapid global spread of obesity reflects a world that has made it easier to consume excess calories and harder to burn them off, a pattern that affects nearly every country regardless of income level. Without large-scale changes to food policy, urban planning, and healthcare access, projections suggest the numbers will continue climbing well into the 2030s and beyond.